1. Field of the Invention
The present invention relates generally to systems for guiding one part relative to another in an accurately defined path and, more particularly, to such a system incorporating a fluid spring that eliminates friction on heretofore found moving parts.
2. The Prior Art
In the machining tool industry, workpieces sometimes must be cut and formed to extremely accurate dimensions. Such work requires that one movable part traverses an extremely accurately defined path relative to another part. This in turn requires that the latter part be provided with opposed sides that are both straight and parallel for engagement by the opposed surfaces of the movable part. Deviations in the opposed sides do occur however. Consequently, it is not only difficult but also is rather expensive to provide a path whose opposed surfaces are exactly straight and parallel to one another. This is especially so the greater is the required length of the accurately defined path.
Two known systems of an affiliated company have addressed this problem. In U.S. Pat. No. 3,578,827, an accurate guiding system is disclosed which comprises two bearings carried by one component and positioned adjacent two opposed walls of the second component. One of the bearings is mounted on a rigid bar adjacent the accurate side. The other bearing is connected to the first by a solid but resiliently mounted bar, giving it freedom to float on the not so accurate surface. The path of movement is controlled by the rigidly mounted bearing, with the second bearing floating to accommodate dimensional differences. In U.S. Pat. No. 4,378,134, the bearings are piston-mounted air bearings, one being fixed, the other floating.
Both systems achieve the desired objective. Both do so with complexity and expense, however. In addition, both involve some friction occasioned by the presence of moving parts in the bearings. There is thus room for improvements.